In the event of an emergency situation aboard a large commercial passenger airplane where evacuation of the passengers and crew becomes necessary, emergency escape slides are typically used. These escape slides are typically stored inside the passenger doors of the airplane. Prior to normal operations for embarking and disembarking passengers at the airport terminal gate, the emergency escape slides are disarmed. This allows the cabin doors to be opened and closed in a normal manner without activating the emergency escape slides.
However, once the airplane leaves the airport terminal gate, the emergency escape slides are armed. Arming the emergency escape slides causes a metal girt bar attached to the girt at the upper end of each slide to be connected to the floor of the airplane cabin. In the event of a situation requiring emergency evacuation of the passengers and crew from the airplane, each emergency escape slide is deployed by moving the door handle connected to the inside of the cabin door to the open position to thereby open the door, causing the uninflated escape slide to fall from its storage pack inside the cabin and inflate outside the airplane. Since the upper end of the inflating escape slide is attached to the girt bar, the escape slide remains connected to the airplane.
During inflation, the escape slide has a tendency to pop open thereby resulting in a significant force being applied to both the girt and the girt bar. Once the slide is inflated, the weight of passengers, crew, equipment, and so on can also create significant loads on both the girt and girt bar.
As shown in FIG. 1, a typical prior art solution includes an escape slide 10 releasable connected to the fuselage 12 (shown in phantom line) of an aircraft by a girt 14 that extends from the doorway (not shown) of the aircraft, wraps around a first sill tube 16, and is cemented, sewn or otherwise connected at one end to the floor 18 of the escape slide. An opposite end (not shown) of the girt 14 is wrapped around a girt bar (not shown) along the entire length thereof. The girt bar is in turn connected to the floor of the aircraft when the escape slide 10 is armed or deployed. Such an arrangement creates an interface between the inflatable slide and the respective aircraft. The loads from slide deployment, passenger egress, wind, and/or water are transmitted through the fabric of the girt into the girt bar and consequently into the floor fittings of the aircraft.
One drawback of such a prior art solution is that when an inflatable slide is loaded, a uniform load is applied across the length of the girt bar which is suspended at its opposite ends. This arrangement results in a substantial bending moment at the center of the bar. Consequently, the girt bar tends to flex and, if inadequately designed, could lead to catastrophic failure. Accordingly, the strength of the material as well as the cross-sectional area and shape of the prior art girt bar must be taken into account during the design process and is typically based on the maximum load generated during sliding tests plus a predefined safety factor. As a consequence, heavy girt bars capable of withstanding such loads are typically required in the prior art evacuation arrangements.
In addition, prior art girts may experience point sources of loading, causing tearing of the fabric and consequent failure. Also, in the event of a water landing, some prior art solutions require release of the entire girt bar itself from the aircraft in order to release the inflated evacuation slide, while other prior art solutions employ a complicated two-piece girt with a series of loops and webbing arranged in a daisy chain that extends across the entire girt bar for release therefrom. Such a solution is complicated to construct, difficult to maintain and awkward to deploy, especially in emergency situations where time is of the essence.